ml86v7668 Oki Semiconductor, ml86v7668 Datasheet - Page 9

• Manufacturer Part Number: ml86v7668
• Description: Ntsc/pal/secam Digital Video Decoder
• Manufacturer: Oki Semiconductor

FUNCTIONAL DESCRIPTION
This section explains the basic functions of the IC in terms of the blocks shown in the block diagram.
Refer to the User's manual for detailed explanations of the internal registers and any functions that are not covered
in this data sheet.
Analog Section
The analog section inputs video signals. The analog section uses the video signal channel selector, AMP and 10-bit
ADC to select the desired channel from among several video signals and convert the input to digital video data.
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Digital Section
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2-dimensional Y/C Separation Block
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OKI Semiconductor
Analog input selector
Clamp function
AMP/analog AGC function
A/D converter
Decimation filter
2-Dimensional Y/C Separation Function
The analog input selector is compatible with composite signals and S-video signals. The maximum number of
input connections is 4 channels of composite signals or 3 channels of S-video signals + 1 channels of composite
signals. The selection of these input connections can be changed by external pins or by register controls using
the I
# Related register: $68/ADC1[2:0]
The clamp fixes the video input signal in the ADC input range. Clamping is performed by sync chip clamp.
This function converts video input signals to the optimum level for the ADC using the analog AMP of the AGC
function. The AGC function has an output level adjust function in the luminance block of the digital section in
addition to the AMP input level adjust function. Manual setting of the AMP gain is also possible.
# Related register: $69/ADC2
This 10-bit A/D converter (ADC) converts analog video signals to digital video data. There are 2 channels
built into the ADC. Sampling is performed at the pixel frequency or double-speed.
# Related registers: $68/ADC1, $69/ADC2, $6A/ADC3
The digital section separates the video data digitized by the ADC into Y and C data, converts these data to
various data formats and outputs them. The digital section also performs output level adjustment, image quality
adjustment and various corrections.
Since internal processing is performed at a single speed, this filter is needed to reduce the data that has been
doubled by one-half. Using the decimation filter after double-speed sampling reduces high-frequency noise .
# Related register: $08/FIFOBC[7]
This block separates composite data into Y (luminance) data and C (chrominance) data. For S pin input, Y/C
separation circuit is bypassed. The Y/C separation function works only for lines which are active as image data
and is bypassed for composite signals in the V blanking period.
With the Y/C separation filter, composite data is separated into Y (luminance) data and C (chrominance) data.
There are various Y/C separation filters available, which can be selected in an internal register.
Y/C separation of the SECAM signal is performed by the trap filter.
# Related register: $10/YC1, $11/YC2
2
C-bus.
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